The Rhine Estuary-Drechtsteden region is a densely populated area of immense economic significance to the Netherlands. It is an area of extremes: with port activities, urban areas, the Greenports (horticulture), and the Biesbosch nature reserve.
In this region – around Rotterdam and Dordrecht – water comes from two directions: the sea and the rivers. Economic and spatial development in the Rhine Estuary-Drechtsteden region is only possible if its flood protection , its freshwater supply , and its climate resilience are up to par, in both the short and the long term. The Rhine Estuary-Drechtsteden region has drawn up a Preferential Strategy to that effect. The region has been working on the implementation of this strategy since 2014, within the framework set out by the Delta Decisions.
A number of dyke sections in the Rhine Estuary-Drechtsteden area do not meet the current standards. In recent years, a higher protection level has been agreed upon for most of the dykes, because of the increase in population and economic value behind the dykes. Furthermore, near dyke sections that are constructed on peat, subsidence causes additional tasking in terms of safety. In the Rhine-Estuary-Drechtsteden region, the flood risk management tasking is focused on the area around Rotterdam, Krimpenerwaard, Alblasserwaard-Vijfheerenlanden, the Eiland van Dordrecht, and the island of Voorne-Putten. Climate change will result in longer periods of drought, which will put additional pressure on the freshwater supply in the area. Finally, the region is faced with a spatial adaptation tasking, inter alia, in the areas outside the dykes.
Preferential Strategy for Flood Risk Management
As the elevation of the Rhine Estuary-Drechtsteden region is quite low, most areas will be submersed very quickly and to a substantial depth in the event of a flood. Flood prevention is therefore of great importance. This can be achieved by consistently choosing the best combination of three types of preventive measures: storm surge barriers, dykes, and river widening.
The Hollandsche IJssel remains an open river which can be closed off by a storm surge barrier. This provides the best opportunities for flood risk management, shipping, and the tidal ecology. A broad-based study will be conducted into the replacement of the Maeslant storm surge barrier in the Nieuwe Waterweg. One of the alternative solutions to be explored, along with replacing the storm surge barriers, involves the introduction of sea locks. This study is expected to commence around 2040. The Delta Programme monitors new insights in the fields of climate change, flood risk management, and freshwater supply; if need be, the study will be launched at an earlier date.
In addition to limiting the flood risk, water-resilient spatial design adaptations are also being prepared. Disaster management requires additional attention in order to protect, inter alia, the power grid and high-risk businesses in the event that things go wrong nonetheless in this complex and densely populated area.
A special feature of the Rhine Estuary-Drechtsteden region is the long stretches of areas outside the dykes which are densely populated and offer many employment opportunities. These areas are not protected by the dykes. The region will devote additional attention to measures aimed at limiting loss as well as communication regarding the risks run by the residents.
Typical of the approach adopted in this region is that water issues and spatial development are considered in an inter-connected manner.
For its freshwater supply, the western part of the Netherlands is dependent on a limited number of locations where freshwater from the rivers is let in (inlet points). The main inlet points are those near Gouda and Bernisse. In the future, these inlet points will become less reliable, because the water is increasingly salinising. At the same time, demand for fresh water is likely to increase. The freshwater supply to the western Netherlands will remain up to par by gradually expanding the emergency supply from the Waal and the Amsterdam-Rijn canal. The plans for this so-called Capacity Expansion of the Central Netherlands Climate-proof Water Supply are making steady progress.
The freshwater supply from the Brielse Meer lake will gradually become more resilient: its management will be optimised in the near future. In addition, an improved monitoring system will be introduced, and near Spijkenisse an additional water inlet will be put into operation. The water manager will implement “smart water management” to reduce salinisation in the Hollandsche IJssel, the Amsterdam-Rijn canal, the Noordzee canal, and near the Hagestein weir. In addition, consumers need to economise in their use of water by capitalising on innovations.
The Rhine Estuary-Drechtsteden region is also working on climate resilience. These are some of the measures and projects:
- Three-quarters of the municipalities in West-Netherlands have conducted a stress test. Some have already started to draw up a strategy. In addition, the province of Zuid-Holland and Rijkswaterstaat are working on stress tests for roads, waterways, and bridges;
- The municipality of Dordrecht has elaborated seven climate adaptation pilot projects;
- In Barendrecht, a new square featuring underground water storage is improving the city’s climate resilience;
- The Amsterdam Metropolitan Area has drawn up a climate adaptation implementation agenda. In the Noord-Holland area, the Rijnland district water control board is setting up active working regions, in collaboration with the municipality, to embark on climate adaptation;
- Several district water boards have achieved concrete successes with the Smart Water Management measure. Efficient collaboration minimised waterlogging during the extreme precipitation in early 2018;
- The municipality of Nieuwegein has drawn up a climate vision that serves as an example to other municipalities ;
- The municipality of Woerden has drawn up a concrete Climate Adaptation action plan.
Flood Risk Management implementation agenda
One of the components of the Preferential Strategy for flood risk management is an implementation agenda . Some of the measures featuring on this agenda:
- Alblasserwaard-Vijfheerenlanden study
The parties involved in this study have explored smart ways of combining spatial and economic developments in this area with raising and improving the dykes. In 2018, they will present a collective perspective memorandum, based on the three building blocks: Traffic on the Dykes, Quality of the Dykes and Embankments, and Multi-Layer Flood Risk Management. View the film Volop verbindingen tussen water en ruimte in Alblasserwaard-Vijfheerenlanden [Plenty of connections between water and spatial planning in Alblasserwaard-Vijfheerenlanden], in Dutch.
- Eiland van Dordrecht study
The MIRT [Multi-Year Programme for Infrastructure, Spatial Planning, and Transport] Study into the operationalisation of the strategy to enhance the coping capacity of Eiland van Dordrecht has been completed. According to the study, a “smart combination” of dykes, spatial planning adjustments, and an additional focus on disaster control would not be advisable here. The investment expenditure related to additional reinforcement of the regional dykes outweighs the expenditure involved in additional reinforcement of the primary dyke. However, the parties involved will continue their collaboration on other opportunities for multi-layer flood risk management.
- Strategic adaptation agenda for the area outside the dykes
In 2017, the municipality of Rotterdam drew up a strategic adaptation agenda for the area outside the dykes, in concert with the regional stakeholders. One of the follow-up actions is the development of area-specific flood risk management strategies for all the areas outside the dykes in this region. A pilot study has already produced such a strategy for the Botlek area. View the film Wonen en werken in buitendijks gebied - Samenwerken aan een waterveilige toekomst [Living and working outside the dykes – collaborating on a flood-proof future], in Dutch.
- Disaster control
In the purview of the Water and Evacuation project, the Security Regions are mapping out the disaster control tasking. Dordrecht has already drawn up a flood risk management plan as a pilot project; the Zuid-Holland Zuid Security Region has joined forces with other stakeholders to develop a similar plan for the Alblasserwaard-Vijfheerenlanden area. The Rotterdam-Rhine Estuary Security Region has conducted a case study to substantiate improvements in flood disaster management.
- Maeslant storm surge barrier
The Maeslant storm surge barrier plays a key role in protecting the area from flooding. Rijkswaterstaat has conducted a study into the reduction of the probability of failure and into the partial closure of the Maeslant storm surge barrier. The options for partial operation of the Maeslant storm surge barrier, such as closing one of the two sector doors, will serve as a back-up measure to stem a maximum of water when extreme weather necessitates closure of the barrier. The outcomes have prompted Rijkswaterstaat to further explore which measures can be implemented in interconnection with the dyke security tasking.
The Geuzenlinie project is aimed at combining recreational activities, traffic, and a (specific) demand for work space with water storage. In early 2017, the municipalities of Brielle, Hellevoetsluis, Nissewaard, and Westvoorne embarked on the Geuzenlinie Regional Programme at the northern rim of the island of Voorne-Putten.
- Hollandsche IJssel integrated approach
In 2018, Rijkswaterstaat and the Schieland en de Krimpenerwaard district water control board rolled out a study into further options to improve the Hollandsche IJssel storm surge barrier and their impact on the Hollandsche IJssel flood risk management tasking.
- River as a tidal park
The project focuses on softening and greening the – currently usually stony – embankments. Using natural processes is beneficial to nature development and recreation, and improves flood protection at a number of locations.
- Rhine-Meuse estuary study
At the request of the House of Representatives (Geurts motion), an additional study has been conducted into closing the Rhine-Meuse estuary on the seaward side, as a long-term option. This option involves locks in the Oude Maas and Nieuwe Maas, in combination with peak water storage in the Oosterschelde. The conclusion is that this alternative warrants a fully-fledged exploration when the study into replacement of the Maeslant storm surge barrier is launched (the study is expected to commence in 2040). The Delta Programme is monitoring new insights relating to climate change, flood risk management, and freshwater supply; if need be, the study will commence at an earlier date.
In addition to these projects and studies, further ambitions have been set down regarding the topics of Water & Spatial Planning, Storm surge barriers, Areas Outside the Dykes, Spatial Adaptation, Disaster Control, and Adaptive Delta Management. Each ambition is coordinated by one of the regional parties, in collaboration with the other stakeholders. Plans of approach set out the actions involved in each of the ambitions in more concrete terms.
Two pilots in the Rhine Estuary-Drechtsteden region have been awarded European Interreg grants. The grants were provided under European programmes focused on multi-layer flood risk management (FRAMES) and climate adaptation (BEGIN), in which the province of Zuid-Holland and the municipality of Dordrecht, respectively, are participating.